Mobile machines are used to perform a variety of tasks. As an example, in an earthworking environment such as a mining site, mobile machines, e.g., off-road mining trucks, haul material throughout the site.
For repetitive tasks such as above, it is becoming advantageous and desirable to operate the mobile machines autonomously. The environment in which the trucks operate may be harsh, and more efficient operations may be attained if the human fatigue factor is eliminated.
As an example of using off-road mining trucks autonomously, U.S. Pat. No. 5,612,883, issued to Shaffer et al., provides an exemplary disclosure of a system for autonomous operations of mobile machines. In this patent, Shaffer et al. disclose a fleet of off-road mining trucks operating autonomously at a mining site. Parameters such as position determination, navigation, path planning, and machine control are performed without the aid of human operators.
An important factor in enabling a mobile machine to operate autonomously is the ability to detect obstacles in the machine's path of travel, and to respond in an acceptable manner when obstacles are detected. The normal course of action when encountering an obstacle is to stop the mobile machine and notify a fleet manager to remove the obstacle. However, this is not always the most efficient course of action. Under some circumstances, stopping the mobile machine may not be necessary, particularly when the obstacle is moving and may soon be out of the path of the mobile machine.
An appropriate response to the detection of an obstacle may vary dependent on the location of the obstacle relative to a mobile machine. A more efficient method for responding to a detected obstacle would be to vary the response as a function of the detected obstacle being in one of a plurality of zones relative to the location of the mobile machine. As an example of using zones of detection, in U.S. Pat. No. 5,521,633, Nakajima et al. disclose the use of a series of zones in the scan pattern of an obstacle detector, each of the zones having a corresponding "rate of danger" of an obstacle detected in the zone. A method for alerting an operator to the presence of an obstacle varies in response to a determination of which zone the obstacle is in.
However, the disclosure of Nakijima et al. does not account for the detected obstacle moving from one zone to another, or to predicting the movement of the obstacle between zones. Responding appropriately and efficiently to the detection of an obstacle, more particularly a moving obstacle, would improve greatly if the movements of the detected obstacle were predictable and could be responded to prior to the obstacle entering a zone.
The present invention is directed to overcoming one or more of the problems as set forth above.